Quantum antiferromagnet bluebellite comprising a maple-leaf lattice made of spin-1/2 Cu$^{2+}$ ions

TL;DR

This study reports the synthesis of a new spin-1/2 maple leaf lattice antiferromagnet, bluebellite, revealing unexpected one-dimensional magnetic behavior that challenges existing understanding of frustration effects.

Contribution

First synthesis of bluebellite as a candidate for maple leaf lattice antiferromagnet with novel emergent one-dimensional magnetic correlations.

Findings

Moderate magnetic frustration with Curie-Weiss temperature of -35 K.

Magnetic transition observed at 17 K.

Evidence of one-dimensional spin correlations above T_N.

Abstract

Spin-1/2 maple leaf lattice antiferromagnets are expected to show interesting phenomena originating from frustration effects and quantum fluctuations. We report the hydrothermal synthesis of a powder sample of bluebellite Cu$_6$IO$_3$(OH)$_{10}$Cl as a first potential candidate. Magnetization and heat capacity measurements reveal moderate frustration with a Curie-Weiss temperature of $-35$ K, and a magnetic transition at $T_N$ = 17 K. Surprisingly, the magnetic susceptibility and heat capacity above $T_N$ are well reproduced by the Bonner-Fisher model, which suggests that a one-dimensional spin correlation with a magnetic interaction of 25 K occurs in the apparently two-dimensional lattice. This emergent one-dimensionality cannot be explained by orbital ordering or dimensional reduction due to geometrical frustration. We believe that there is an unknown mechanism to cause one-dimensionality in the spin-1/2 maple leaf lattice antiferromagnet.